Strong electromagnetic fields are produced in the relativistic heavy
ion collisions [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]}.
One way to describe the evolution of electromagnetic fields is through
the relativistic magnetohydrodynamics consisting of the hydrodynamical
conservation equations coupled with Maxwell's equations. The solutions
to equations of ideal magnetohydrodynamics with longitudinal boost
invariance show that the transverse magnetic field decays as \(\sim 1/\tau \) 
with \(\tau \)  being the proper time [10]}, [11]}, [12]}, [13]}, [14]}, [15]}
(for a recent numerical simulation of electromagnetic fields based
on ideal magnetohydrodynamics, see, e.g., Ref. [8]}).
